FIGURE 5.

Models for Py tract recognition by U2AF⁶⁵. A, model of initial 3′ splice site complex derived from biochemical experiments and known interacting domains. BPS, branch point sequence; RS, RS domain. B, most typical (lowest NSD) BUNCH model of wtU2AF⁶⁵R12, colored in a blue-to-red gradient from N terminus (N) to C terminus (C), overlaid with a representation of the solvent-accessible surface. Asterisks mark the junctions of the RRMs with the ab initio linker (green). The N and C termini are restricted to extend from adjacent regions of the modeled polypeptide by the physical limitations of the intermediary linker. C, a model for adaptable recognition of diverse natural Py tracts by adjustment of the U2AF⁶⁵ inter-RRM configuration.